HAVANA (Reuters) - Former U.S. President Jimmy
Carter will begin a three-day visit to Cuba Monday for what
is described as a "private, non-governmental mission" where the
main topic may be the fate of a U.S. aid contractor jailed for
setting up illegal Internet service.

The timing, coming shortly after contractor Alan Gross was
sentenced to 15 years in a Cuban prison, and Carter's past as
an unofficial diplomatic troubleshooter suggest he will
intervene on Gross's behalf, although no one has said so
publicly.

The Carter Center said Cuba invited him down to "learn
about new economic policies and the upcoming (Communist) Party
congress and to discuss ways to improve U.S.-Cuba relations."

Gross is a major stumbling block for the longtime
ideological enemies because the United States has said
relations, which warmed modestly before his arrest, are on hold
until he is free.

After arrival with wife Rosalynn, Carter's first public
event will be with Havana's Jewish community, supposedly the
recipient of Gross's help in setting up Internet service under
a U.S.-funded program outlawed in Cuba.

Then he will see Cuban Catholic leader Cardinal Jaime
Ortega, whose talks with President Raul Castro last year
resulted in the release of most of the island's political
prisoners.

On Tuesday, Carter, 86, will converse with Castro, 79,
before a Wednesday press conference and his departure.

Castro is in the midst of preparing for a Communist Party
congress in April where reforms to Cuba's Soviet-style economy
are expected to be approved.

Neither Gross nor former leader Fidel Castro were on the
schedule issued by the Cuban government, but Carter seems
likely to meet with them and perhaps Cuban dissidents as well.

He has played a mediating role in other international
problems, including last August when he went to North Korea to
secure the release of an American imprisoned there.

RESPECTED BY THE CASTROS

There has been no indication he is coming to Cuba at the
behest of U.S. President Barack Obama, so it is not clear what
he can offer the Cubans, but he is respected by the Castros.

In a 2002 visit he called for an end to the longstanding
U.S. trade embargo against the island, but also said Cuba
needed democracy and better human rights, and gave dissidents a
boost by publicly mentioning their movement.

While in the White House, he took steps such as lifting a
general ban on U.S. travel to Cuba and remains the only U.S.
president, in or out of office, to visit the island since the
1959 revolution that turned it into a communist state.

What Carter could do, said John McAuliff of the New
York-based Fund for Reconciliation and Development, is act as
an intermediary between the U.S. and Cuban governments.

"Hopefully, Carter can close the gap, not only by
facilitating a humanitarian resolution of the Alan Gross case,
but also by encouraging a positive response from Washington,"
said McAuliff, who advocates improved U.S.-Cuba relations.

Obama has eased U.S. travel restrictions to Cuba and
restarted talks on migration and postal issues, but McAuliff
said more steps, such as removing the island from the list of
terrorist-sponsoring countries, are needed.

Gross, 61, was in Cuba working under a U.S. program
promoting political change on the island, which Cuba views as
subversive.

A Cuban court this month found he committed "acts against
the independence and territorial integrity of the state" and
gave him a 15-year sentence.

The U.S. has said he was in Cuba only to provide Internet
access to Jewish groups and committed no crime. It has
demanded his release, which many think Cuba is willing to do
because it made its point about displeasure with the U.S.
pro-democracy programs and because of humanitarian concerns.

Gross's 26-year-old daughter and 88-year-old mother have
been diagnosed with cancer since his arrest in December 2009.

Wife Judy Gross said on Saturday the family was "desperate
for his return home."
(Reporting by Jeff Franks, editing by Anthony Boadle)